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Chapter 1

Chapter 1.doc


Department
Nutrition
Course Code
NUTR 2050
Professor
Simone Holligan
Chapter
1

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Chapter 1: Nutrition Through the Life Cycle
Introduction
Nutrition is a interdisciplinary science focused on the study of nutrients and other constituents and health
Nutrients: chemical substances in foods that are used by the body for growth and health
Principles of the Science of Nutrition
Look at table 1.1 on PG 2
Principle #1 Food is a basic need for humans
People need enough food to live
The right assortment of food for optimal health
People with enough food= food security
Food security: access at all times to a sufficient supply of safe nutritious foods
Food insecurity: limited or uncertain availability of safe nutritious foods, or the ability to acquire them in socially acceptable
ways
12% of U.S households are food insecure
Principle #2 Foods provide energy (calories), nutrients and other substances needed for growth and health
1 reason why people eat= the requirement of calories (energy), nutrients and other substances supplied by foods for growth and
health
Calories: a unit of measure of the amount of energy supplied by food. Known as kilocalories (kcal) or large calories
Calories are unit not a substance
Nutrients = chemical substances= variety of functions that support growth tissue maintenance and repair for ongoing health
6 categories of nutrients- look at table 1.2 for details
1. Carbohydrates
2. Proteins
3. Fats (lipids)
4. Vitamins
5. Minerals
6. Water
Essential and Nonessential Nutrients
Essential Nutrients: substances required for growth and health that cannot be produced, or produced in sufficient amounts by the
body. They must be obtained from the diet
Essential= required in the diet
Essential Nutrients
-Carbohydrates
-Certain Amino Acids (Essential amino acids:
phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, leucine, lysine, and histidine.)
-Linoleic acid and alpha linolenic acid (essential fatty acids)
-Vitamins
-Minerals
-Water
Essential Amino Acids: amino acids cannot be synthesized in adequate amounts by humans and therefore must be obtained from
the diet. Also called indispensible amino acids
Nonessential Nutrients: nutrients required for growth and health that can be produced by the body from other components of the
diet
Ex: cholesterol, creatine and glucose
Do not have to be apart of the diet
Some play an important role for maintaining health
Requirements for Essential Nutrients:
All humans need the same set of nutrients
The amount of nutrients varies based on:

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Age Illness
Body size Lifestyle habits
Gender Medication Use
Genetic Traits Pregnancy and
lactation
Growth
Dietary Intake Standards
Cannot take into account all of the factors that influence nutrient needs
Do account for age, gender, growth and pregnancy and lactation\
Intake standards= Dietary Reference Intake (DRIs)
-(DRIs): used for the nutrient intake standards for healthy people
-Recommended Dietary Allowances (RDAs): levels of essential nutrients intake judged to meet nutrient needs of all healthy
people while decreasing the risk of chronic diseases
-Adequate Intake (AIs): Tentative RDAs. Less conclusive scientific info then RDAs
-Estimated Average Requirements (EARs):values that are estimated to meet requirements of half the healthy individual.
They assess adequacy of intakes of the populations groups
-Tolerable Upper Intake (ULs): upper limits of nutrient intake. Represent total, daily levels of nutrients intake from food,
fortified foods and supplements that should not be exceeded
-ULs: asses the safety of high intakes of nutrients, particularly from supplements
DRIs are levels of nutrients intake intended for use as a reference values for assessing diets for healthy people
RDAs = intake levels that meet nutrients needs over 98%
EARs should not be used to examine the possibility of inadequate intake in individuals and groups
Standards of Nutrient Intake for Nutrition
Daily Values (DVs): scientifically a agreed upon standards for daily intakes of nutrients from the diet developed for use on
nutrition labels
Used to identify the amount of a nutrient provided in serving food “%DV”
Percentages obtained from one serving of food product
Carbohydrates
Used as a source of readily available energy
Simple sugars= monosaccharide’s and disaccharides
Complex Carbohydrates= polysaccharides
-Starches (plant form of stored carbs)
-Glycogen (animal forms of stored carbs)
- Most types of Fiber
Dietary sources of fiber
Alcohol sugars
Basic carbs= single molecules= monosaccharide’s:
-Glucose= blood sugar and dextrose
-Fructose= fruit sugars
-Glactose
Disaccharides= two monosaccharide
-Sucrose: glucose+ fructose i.e. Table sugar
-Maltose: glucose+ glucose i.e. Malt sugar
-Lactose: glucose+ galactose i.e. Milk sugar
Complex carbs: 4 calories per gram
Large intestine digest some dietary fibers and excrete fatty acids used for energy
The main function of fiber is for bulk for normal elimination
High fiber diets reduce the rate of glucose absorption
High fiber may help prevent cardiovascular disease and some types of cancer
Xylitol, mannitol, and sorbitol= forms of alcoholic sugars
Small amounts are needed to sweeten beverages, gums and yogurt
Alcoholic sugars do not promote tooth decay

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Alcohol (consumed as ethanol)
Product of fermentation of sugar with yeast
Has 7 calories per gram
Gylcemic Index of Carbohydrates and Carbohydrates in Foods
Some simple and complex carbohydrates in foods elevate blood glucose levels more than others do
Important for people with:
-Insulin Resistance: a condition in which the cell membrane have reduced sensitivity to insulin than the normal that is required to
transport a given amount of glucose into a cells
-Type 2 Diabetes: a disease characterized by high blood glucose levels due to body inability to use insulin normally, to produce
enough insulin or both
Carbohydrates and carbohydrate containing food= classified by to the extent they raise blood glucose levels
Classification system= Glycemic Index: a measure of the extent to which blood glucose is raised to a 50- gram portion of a
carbohydrate containing food compared to 50 grams of glucose or white bread
Carbs digested and absorbed quickly = high glycemic index
Diets= Low glycemic index= found to improve blood glucose control with people with diabetes
Reduce elevated levels of blood cholesterol and triglycerides
Increase good HDL cholesterol
Decrease the risk of developing diabetes, some types of cancer and heart disease
Recommended Intake Level
Intake of crabs= based on contribution to total energy intake
Recommended that 45- 65% of calories come from crabs
Added sugars= 25% of caloric intake
For Females 21 and 25 grams of dietary fiber daily
For males 30 – 38 grams of fiber daily
Food Sources of Carbohydrates
Distributed in plant foods
Milk (lactose) is a animal source of crabs
Additional info about crabs and fiber of foods can be found on nutrition labels
Protein
Provides the body with amino acids
Amino Acids: the “building blocks” of protein. Unlike crabs and fats, amino acids contain nitrogen
Build and maintain tissues such as muscles, bones, enzymes and red blood cells
Can be used as a source of energy – not primary function
4 calories per gram
9 amino acids= produced by the diet= essential amino acids
Body manufactures amino acids obtained from foods= nonessential amino acids
Foods of high quality protein= assortment= milk, cheese, meat, eggs and other animal fats
Plant sources do not provide the 9 essential amino acids except soybeans
Plant sources in combinations= grains and seeds with dried beans= high quality protein
These are examples of “complement” protein
Recommended Protein Intake
DRIs= 10- 35% of total energy
Protein Deficiency:
-Rare in developed countries
-Leads to loss of muscle tissue, growth failure, weakness, reduced resistance to disease, kidney and heart problems
-In adults= loss of body tissue protein, heart abnormalities, diarrhea and other health problems
-Kwashiorkor: a severe form of protein energy malnutrition in young children in young children. It is characterized by
swelling fatty liver; susceptibility to infection, profound apathy and poor appetite. The cause is unknown
Food Sources of Protein
Animal products
Dried beans
Listed in table 1.6
Fats (lipids)
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